1. Field of the Invention
The present invention relates to a network control system, a network control method, and a computer product that effectively carry out a searching process.
2. Description of the Related Art
Technologies have been suggested which enable, upon receiving a large number of search conditions from a plurality of users, to combine the search conditions that can be combined and to carry out a collective search instead of using the respective search condition to carry out the search separately.
For example, in a method disclosed in Japanese Patent Application Laid-open No. H11-120190, a searching process is carried out on a plurality of text files that include a hierarchical structure due to a description using SGML (Standard Generalized Mark-up Language). In other words, upon receiving the search conditions that use a combination of an entry name that indicates a layer of a hierarchy and a keyword that is included in a text file that is indicated by the entry name, when searching the text files that satisfy the search conditions, the method mentioned earlier efficiently processes a large number of the search conditions received from the users. To be specific, the entry name of the search condition is treated as a new entry name by using an entry name that is in a lower layer of the hierarchy than the entry name, a search condition is generated using a combination of the entry name and the keyword, and the overlapped search conditions are combined into a single new search condition. Thus, the multiple search conditions are efficiently processed.
Further, in a method that is disclosed in Japanese Patent Application Laid-open No. H6-325093, the same search conditions are integrated and the searching process of the same content is not executed repeatedly. In other words, in the searching process that is called a reserved search and that is carried out by a data searching system, new data is sequentially added to the data searching system. A terminal prior receives the search conditions and uses the received search conditions to execute the search whenever the new data is added. In the reserved search, the same search conditions, among the prior received search conditions, are integrated and the searching process of the same content is not executed repeatedly.
Further, in a network control system that is explained in detail below, upon receiving a large number of the search conditions from the multiple users, data collectors included in the network control system combine the search conditions that can be combined to realize the searching process that carries out a collective search.
To be specific, as shown in FIG. 22, the network control system includes data controllers 10a1 to 10an that store therein data that is a search target, request terminals 20a1 to 20am that execute various processes according to instructions from the users, data collectors 30a1 to 30ak that search from the data controllers 10a1 to 10an, data that matches the search conditions, and a load-dispersing device 40 that disperses a searching process load of the data collectors 30a1 to 30ak. 
In the network control system, upon receiving the search conditions via an input unit from the users, a request terminal 20ax transmits the search conditions to the load-dispersing device 40.
Upon receiving the search conditions from the request terminal 20ax, the load-dispersing device 40 selects a destination data collector 30ax such that the searching process load is equally shared by all the data collectors 30a1 to 30ak, and transmits the search conditions to the selected data collector 30ax. In other words, the load-dispersing device 40 equally transmits the search conditions to the data collectors 30a1 to 30ak to ensure that a receipt count of the search conditions in the data collectors 30a1 to 30ak is not biased for a prolonged time period.
Upon receiving the search conditions from the load-dispersing device 40, based on the search conditions, the data collector 30ax accesses a data controller 10ax, reads search target data that indicates data that matches with the search conditions, and transmits the read search target data to the load-dispersing device 40. Upon receiving the search target data from the data collector 30ax, the load-dispersing device 40 transmits the search target data to the request terminal 20ax that is a destination of the search conditions corresponding to the search target data. Finally, upon receiving the search target data from the load-dispersing device 40, the request terminal 20ax responds to a user request by generating a predetermined screen in a display unit.
However, the searching process in the network control system mentioned earlier is inefficient. In other words, although a load-dispersing device reduces the searching process load of each data collector by equally transmitting the search conditions, sometimes the load-dispersing device transmits the same search conditions to the multiple data collectors. Due to this, the searching process is carried out by the multiple data collectors and is overlapped. The searching process cannot be carried out efficiently even if the searching process is carried out by using the methods mentioned earlier.